Introduce the description of a hwtstamp provider, mainly defined with a
ptp_clock pointer and a qualifier value.

Add a hwtstamp provider description within the netdev structure to
allow saving the hwtstamp we want to use. This prepares for future
support of an ethtool netlink command to select the desired hwtstamp
provider. By default, the old API that does not support hwtstamp
selectability is used, meaning the hwtstamp ptp_clock pointer is unset.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
---

Change in v8:
- New patch

Change in v10:
- Set hwtstamp in netdevice as a pointer for future use of rcu lock.
- Fix a nit in teh order of setting phydev pointer.
- Add a missing kdoc description.

Change in v13:
- Remove an include from netdevices.h.

Change in v16:
- Import the part of the patch 12 which belong to the hwtstamp provider
  selectability of net core.

Change in v18:
- Fix a doc NIT.
---
 drivers/net/phy/phy_device.c     | 11 +++++++++
 drivers/ptp/ptp_clock_consumer.c | 10 ++++++++
 include/linux/net_tstamp.h       | 18 +++++++++++++++
 include/linux/netdevice.h        |  5 ++++
 include/linux/ptp_clock_kernel.h | 10 ++++++++
 include/uapi/linux/net_tstamp.h  | 11 +++++++++
 net/core/dev_ioctl.c             | 43 ++++++++++++++++++++++++++++++++--
 net/core/timestamping.c          | 50 ++++++++++++++++++++++++++++++++++++----
 8 files changed, 151 insertions(+), 7 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 563497a3274c..c8440168cb09 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -32,6 +32,7 @@
 #include <linux/phy_link_topology.h>
 #include <linux/pse-pd/pse.h>
 #include <linux/property.h>
+#include <linux/ptp_clock_kernel.h>
 #include <linux/rtnetlink.h>
 #include <linux/sfp.h>
 #include <linux/skbuff.h>
@@ -1998,6 +1999,16 @@ void phy_detach(struct phy_device *phydev)
 
 	phy_suspend(phydev);
 	if (dev) {
+		struct hwtstamp_provider *hwtstamp;
+
+		hwtstamp = rtnl_dereference(dev->hwtstamp);
+		/* Disable timestamp if selected */
+		if (hwtstamp && ptp_clock_phydev(hwtstamp->ptp) == phydev) {
+			rcu_assign_pointer(dev->hwtstamp, NULL);
+			call_rcu(&hwtstamp->rcu_head,
+				 remove_hwtstamp_provider);
+		}
+
 		phydev->attached_dev->phydev = NULL;
 		phydev->attached_dev = NULL;
 		phy_link_topo_del_phy(dev, phydev);
diff --git a/drivers/ptp/ptp_clock_consumer.c b/drivers/ptp/ptp_clock_consumer.c
index 58b0c8948fc8..f5fab1c14b47 100644
--- a/drivers/ptp/ptp_clock_consumer.c
+++ b/drivers/ptp/ptp_clock_consumer.c
@@ -98,3 +98,13 @@ void ptp_clock_put(struct device *dev, struct ptp_clock *ptp)
 	put_device(&ptp->dev);
 	module_put(ptp->info->owner);
 }
+
+void remove_hwtstamp_provider(struct rcu_head *rcu_head)
+{
+	struct hwtstamp_provider *hwtstamp;
+
+	hwtstamp = container_of(rcu_head, struct hwtstamp_provider, rcu_head);
+	ptp_clock_put(hwtstamp->dev, hwtstamp->ptp);
+	kfree(hwtstamp);
+}
+EXPORT_SYMBOL(remove_hwtstamp_provider);
diff --git a/include/linux/net_tstamp.h b/include/linux/net_tstamp.h
index 662074b08c94..077037f9ad0f 100644
--- a/include/linux/net_tstamp.h
+++ b/include/linux/net_tstamp.h
@@ -19,6 +19,22 @@ enum hwtstamp_source {
 	HWTSTAMP_SOURCE_PHYLIB,
 };
 
+/**
+ * struct hwtstamp_provider - Description of a hwtstamp provider object
+ *
+ * @rcu_head: RCU callback used to free the struct.
+ * @dev: device attached to the hwtstamp provider used to put the ptp clock.
+ * @ptp: PTP clock pointer of the hwtstamp provider.
+ * @qualifier: hwtstamp provider qualifier.
+ */
+
+struct hwtstamp_provider {
+	struct rcu_head rcu_head;
+	struct device *dev;
+	struct ptp_clock *ptp;
+	enum hwtstamp_provider_qualifier qualifier;
+};
+
 /**
  * struct kernel_hwtstamp_config - Kernel copy of struct hwtstamp_config
  *
@@ -31,6 +47,7 @@ enum hwtstamp_source {
  *	copied the ioctl request back to user space
  * @source: indication whether timestamps should come from the netdev or from
  *	an attached phylib PHY
+ * @qualifier: qualifier of the hwtstamp provider
  *
  * Prefer using this structure for in-kernel processing of hardware
  * timestamping configuration, over the inextensible struct hwtstamp_config
@@ -43,6 +60,7 @@ struct kernel_hwtstamp_config {
 	struct ifreq *ifr;
 	bool copied_to_user;
 	enum hwtstamp_source source;
+	enum hwtstamp_provider_qualifier qualifier;
 };
 
 static inline void hwtstamp_config_to_kernel(struct kernel_hwtstamp_config *kernel_cfg,
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 8feaca12655e..3e7d0cf4b436 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -81,6 +81,7 @@ struct xdp_metadata_ops;
 struct xdp_md;
 struct ethtool_netdev_state;
 struct phy_link_topology;
+struct hwtstamp_provider;
 
 typedef u32 xdp_features_t;
 
@@ -2033,6 +2034,7 @@ enum netdev_reg_state {
  *	@gro_flush_timeout:	timeout for GRO layer in NAPI
  *	@napi_defer_hard_irqs:	If not zero, provides a counter that would
  *				allow to avoid NIC hard IRQ, on busy queues.
+ *	@hwtstamp: Tracks which PTP performs hardware packet time stamping.
  *
  *	FIXME: cleanup struct net_device such that network protocol info
  *	moves out.
@@ -2443,6 +2445,9 @@ struct net_device {
 	 */
 	struct net_shaper_hierarchy *net_shaper_hierarchy;
 #endif
+
+	struct hwtstamp_provider __rcu	*hwtstamp;
+
 	u8			priv[] ____cacheline_aligned
 				       __counted_by(priv_len);
 } ____cacheline_aligned;
diff --git a/include/linux/ptp_clock_kernel.h b/include/linux/ptp_clock_kernel.h
index 87d8f42b2cc1..cf6a72d2868a 100644
--- a/include/linux/ptp_clock_kernel.h
+++ b/include/linux/ptp_clock_kernel.h
@@ -444,6 +444,14 @@ struct ptp_clock *ptp_clock_get_by_index(struct device *dev, int index);
 
 void ptp_clock_put(struct device *dev, struct ptp_clock *ptp);
 
+/**
+ * remove_hwtstamp_provider() - Put and free the hwtstamp provider
+ *
+ * @rcu_head:  RCU callback head.
+ */
+
+void remove_hwtstamp_provider(struct rcu_head *rcu_head);
+
 /**
  * ptp_find_pin() - obtain the pin index of a given auxiliary function
  *
@@ -532,6 +540,8 @@ static inline void ptp_clock_put(struct device *dev, struct ptp_clock *ptp)
 static inline struct ptp_clock *ptp_clock_get_by_index(struct device *dev,
 						       int index)
 { return NULL; }
+static inline void remove_hwtstamp_provider(struct rcu_head *rcu_head)
+{ return; }
 static inline int ptp_find_pin(struct ptp_clock *ptp,
 			       enum ptp_pin_function func, unsigned int chan)
 { return -1; }
diff --git a/include/uapi/linux/net_tstamp.h b/include/uapi/linux/net_tstamp.h
index 858339d1c1c4..55b0ab51096c 100644
--- a/include/uapi/linux/net_tstamp.h
+++ b/include/uapi/linux/net_tstamp.h
@@ -13,6 +13,17 @@
 #include <linux/types.h>
 #include <linux/socket.h>   /* for SO_TIMESTAMPING */
 
+/*
+ * Possible type of hwtstamp provider. Mainly "precise" the default one
+ * is for IEEE 1588 quality and "approx" is for NICs DMA point.
+ */
+enum hwtstamp_provider_qualifier {
+	HWTSTAMP_PROVIDER_QUALIFIER_PRECISE,
+	HWTSTAMP_PROVIDER_QUALIFIER_APPROX,
+
+	HWTSTAMP_PROVIDER_QUALIFIER_CNT,
+};
+
 /* SO_TIMESTAMPING flags */
 enum {
 	SOF_TIMESTAMPING_TX_HARDWARE = (1<<0),
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index 2128dc7f5bfb..2e472e7b8806 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -6,6 +6,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/net_tstamp.h>
 #include <linux/phylib_stubs.h>
+#include <linux/ptp_clock_kernel.h>
 #include <linux/wireless.h>
 #include <linux/if_bridge.h>
 #include <net/dsa_stubs.h>
@@ -269,6 +270,22 @@ static int dev_eth_ioctl(struct net_device *dev,
 int dev_get_hwtstamp_phylib(struct net_device *dev,
 			    struct kernel_hwtstamp_config *cfg)
 {
+	struct hwtstamp_provider *hwtstamp;
+
+	hwtstamp = rtnl_dereference(dev->hwtstamp);
+	if (hwtstamp) {
+		struct ptp_clock *ptp = hwtstamp->ptp;
+
+		cfg->qualifier = hwtstamp->qualifier;
+		if (ptp_clock_from_phylib(ptp))
+			return phy_hwtstamp_get(ptp_clock_phydev(ptp), cfg);
+
+		if (ptp_clock_from_netdev(ptp))
+			return dev->netdev_ops->ndo_hwtstamp_get(dev, cfg);
+
+		return -EOPNOTSUPP;
+	}
+
 	if (phy_is_default_hwtstamp(dev->phydev))
 		return phy_hwtstamp_get(dev->phydev, cfg);
 
@@ -324,11 +341,33 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,
 			    struct netlink_ext_ack *extack)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
-	bool phy_ts = phy_is_default_hwtstamp(dev->phydev);
 	struct kernel_hwtstamp_config old_cfg = {};
+	struct hwtstamp_provider *hwtstamp;
+	struct phy_device *phydev;
 	bool changed = false;
+	bool phy_ts;
 	int err;
 
+	hwtstamp = rtnl_dereference(dev->hwtstamp);
+	if (hwtstamp) {
+		struct ptp_clock *ptp = hwtstamp->ptp;
+
+		if (ptp_clock_from_phylib(ptp)) {
+			phy_ts = true;
+			phydev = ptp_clock_phydev(ptp);
+		} else if (ptp_clock_from_netdev(ptp)) {
+			phy_ts = false;
+		} else {
+			return -EOPNOTSUPP;
+		}
+
+		cfg->qualifier = hwtstamp->qualifier;
+	} else {
+		phy_ts = phy_is_default_hwtstamp(dev->phydev);
+		if (phy_ts)
+			phydev = dev->phydev;
+	}
+
 	cfg->source = phy_ts ? HWTSTAMP_SOURCE_PHYLIB : HWTSTAMP_SOURCE_NETDEV;
 
 	if (phy_ts && dev->see_all_hwtstamp_requests) {
@@ -350,7 +389,7 @@ int dev_set_hwtstamp_phylib(struct net_device *dev,
 		changed = kernel_hwtstamp_config_changed(&old_cfg, cfg);
 
 	if (phy_ts) {
-		err = phy_hwtstamp_set(dev->phydev, cfg, extack);
+		err = phy_hwtstamp_set(phydev, cfg, extack);
 		if (err) {
 			if (changed)
 				ops->ndo_hwtstamp_set(dev, &old_cfg, NULL);
diff --git a/net/core/timestamping.c b/net/core/timestamping.c
index 3717fb152ecc..f8522fefd468 100644
--- a/net/core/timestamping.c
+++ b/net/core/timestamping.c
@@ -9,6 +9,7 @@
 #include <linux/ptp_classify.h>
 #include <linux/skbuff.h>
 #include <linux/export.h>
+#include <linux/ptp_clock_kernel.h>
 
 static unsigned int classify(const struct sk_buff *skb)
 {
@@ -21,19 +22,38 @@ static unsigned int classify(const struct sk_buff *skb)
 
 void skb_clone_tx_timestamp(struct sk_buff *skb)
 {
+	struct hwtstamp_provider *hwtstamp;
 	struct mii_timestamper *mii_ts;
+	struct phy_device *phydev;
 	struct sk_buff *clone;
 	unsigned int type;
 
-	if (!skb->sk || !skb->dev ||
-	    !phy_is_default_hwtstamp(skb->dev->phydev))
+	if (!skb->sk || !skb->dev)
 		return;
 
+	rcu_read_lock();
+	hwtstamp = rcu_dereference(skb->dev->hwtstamp);
+	if (hwtstamp) {
+		if (!ptp_clock_from_phylib(hwtstamp->ptp)) {
+			rcu_read_unlock();
+			return;
+		}
+
+		phydev = ptp_clock_phydev(hwtstamp->ptp);
+	} else {
+		phydev = skb->dev->phydev;
+		if (!phy_is_default_hwtstamp(phydev)) {
+			rcu_read_unlock();
+			return;
+		}
+	}
+	rcu_read_unlock();
+
 	type = classify(skb);
 	if (type == PTP_CLASS_NONE)
 		return;
 
-	mii_ts = skb->dev->phydev->mii_ts;
+	mii_ts = phydev->mii_ts;
 	if (likely(mii_ts->txtstamp)) {
 		clone = skb_clone_sk(skb);
 		if (!clone)
@@ -45,12 +65,32 @@ EXPORT_SYMBOL_GPL(skb_clone_tx_timestamp);
 
 bool skb_defer_rx_timestamp(struct sk_buff *skb)
 {
+	struct hwtstamp_provider *hwtstamp;
 	struct mii_timestamper *mii_ts;
+	struct phy_device *phydev;
 	unsigned int type;
 
-	if (!skb->dev || !phy_is_default_hwtstamp(skb->dev->phydev))
+	if (!skb->dev)
 		return false;
 
+	rcu_read_lock();
+	hwtstamp = rcu_dereference(skb->dev->hwtstamp);
+	if (hwtstamp) {
+		if (!ptp_clock_from_phylib(hwtstamp->ptp)) {
+			rcu_read_unlock();
+			return false;
+		}
+
+		phydev = ptp_clock_phydev(hwtstamp->ptp);
+	} else {
+		phydev = skb->dev->phydev;
+		if (!phy_is_default_hwtstamp(phydev)) {
+			rcu_read_unlock();
+			return false;
+		}
+	}
+	rcu_read_unlock();
+
 	if (skb_headroom(skb) < ETH_HLEN)
 		return false;
 
@@ -63,7 +103,7 @@ bool skb_defer_rx_timestamp(struct sk_buff *skb)
 	if (type == PTP_CLASS_NONE)
 		return false;
 
-	mii_ts = skb->dev->phydev->mii_ts;
+	mii_ts = phydev->mii_ts;
 	if (likely(mii_ts->rxtstamp))
 		return mii_ts->rxtstamp(mii_ts, skb, type);
 

-- 
2.34.1